The present invention relates to a in-line roller skate, and more particularly to such a in-line roller skate which comprises two wheel frames respectively pivoted to the sole of the boot thereof by rivets to hold a plurality of wheels in a line, two ball socket shells mounted in receiving troughs on the wheel frame to guide the turning of the wheel frames about the respective rivets, and means to limit the turning angle of the wheel frames relative to the boot.
In conventional roller skates, wheels are arranged in pair. When skating, the wheels are moved along two parallel skating lines (see FIG. 2). Because of much contact area between the wheels and the ground, much resistance is produced when skating on a conventional roller skate. Further, the wheels of a conventional roller skate may be struck with stones or foreign objects during skating. Therefore, it is difficult to make a smooth skating on a conventional roller skate. Recently, in-line roller skates have become more and more popular for the advantages of high performance. A in-line roller skate, as shown in FIG. 1, is comprised of a plurality of wheels arranged in a line. The wheels for in-line roller skate commonly have a smoothly curved periphery (see FIG. 3). This design diminishes the contact area between the wheels and the ground. Because the wheels of the in-line roller skate are arranged on a wheel frame in a line, the in-line roller skate can be moved at a high speed. However, this design cannot make the skater take a turn except the skater lifts the toe or heel. When lifting the toe or heel, users must pay attention in order to keep the body in balance. Furthermore, because the wheel frame of a in-line roller skate is a solid frame, a single wheel receives much torque when the skater deflects the roller skate. So the wheel of a in-line roller skate wears quickly with use. Therefore, this conventional in-line roller skate is not durable in use. FIG. 4 shows another structure of roller slate according to the prior art. This structure of roller skate comprises a sole plate fixedly mounted on the sole of the boot thereof to hold a rear wheel and a heel stop (brake pad). A bolt is raised from the sole plate near its front side to hold a bearing and a wheel spring holder. The wheel spring holder has two side lugs. A spherical wheel is coupled between the side lugs on the wheel spring holder. This structure of roller skate allows the skater to freely switch the skating direction. However, it is difficult to keep the roller skate in balance when making a turn or snake skating. Therefore, this structure of roller skate is not suitable for beginners.